Receiver circuits having an optical receiving device are known, in which light incident on the optical receiving device—for example light from an optical waveguide in an optical data transmission system—is detected by the optical receiving device, forming an electrical signal (for example a photocurrent), and the electrical signal is subsequently amplified by the downstream amplifier.
An optical receiver circuit having an optical receiving device and having a downstream amplifier is described, for example, in the article “High Gain Transimpedance Amplifier in InP-Based HBT Technology for the Receiver in 40 Gb/s Optical-Fiber TDM Links” (Jens. Müllrich, Herbert Thurner, Ernst Müllner, Joseph F. Jensen, Senior Member, IEEE, William E. Stanchina, Member, IEEE, M. Kardos, and Hans-Martin Rein, Senior Member, IEEE—IEEE Journal of Solid State Circuits, vol. 35, No. 9, September 2000, pages 1260 to 1265). At the input of this receiver circuit there is a differentially operated transimpedance amplifier, that is to say a differential amplifier, one input of which is connected to a photodiode as receiving device. The other input of the differentially operated transimpedance amplifier is connected to a DC amplifier which feeds a “correction current” into the differential amplifier for the purpose of offset correction of the photodiode's photocurrent.
The article by A. Schild et al.: “Amplifier Array for 12 Parallel 10 Gb/s Optical-Fiber Links Fabricated in a SiGe Production Technology”, International Microwave Symposium 2002, describes, inter alia, the design of a transimpedance amplifier in a receiver circuit. A transimpedance amplifier of this type is furthermore described in A. Schild et al.: “High-Gain SiGe Transimpedance Amplifier Array for a 12×10 Gb/s Parallel Optical Fiber Link”, IEEE Journal of Solid State Circuits, January 2003, Vol. 38, Number 1, pages 4-12.
The required bandwidth needs to be taken into account when determining an optimum gain value for a transimpedance amplifier. A high gain is possible when the bandwidth is narrow, whereas only a low gain can be achieved when the bandwidth is wide. This is due to the fact that, to a first approximation, the gain-bandwidth product (V*B) is approximately constant and is prescribed by the individual configuration of the receiver circuit.
Therefore, if a particular bandwidth has been prescribed or is at least to be achieved, the user can derive the maximum permissible gain therefrom. However, the gain of a transimpedance amplifier can be set only within a limited range. This also means that the gain can be optimized with respect to the bandwidth only within a limited range.
There is a need for receiver circuits which can also be optimally used for greatly varying transmission rates.